Charset is: 0 1 2 3 4 5 6 7 8 9 - _ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z a b c d e f g h i j k l m n o p q r s t u v w x y z Rules for string:...

vishal1@vishal.com

aA1@

this regex match numbers, whitespaces and the plus caracter.

Useful for pulling user mentions out of markdown.

With optional 9 digit

FEN is "Forsyth-Edwards Notation"

RE to validate the format of a WGS84 datum coordinates string.

Changes extension in a file name.

trying to learn regex

Here, it matches ft or ft. & foot & feet